Process for the production of photographic images in the presence of compounds of the thiadiazole series

ABSTRACT

PROCESSED PHOTOGRAPHIC SILVER IMAGES ARE STABILIZED BY THE ADDITION OF ANTIBRONIZING AGENTS AGAINST LOSS OF DENSITY AND CHANGES IN IMAGE TONE UPON HIGH GLOSS DRYING AT HIGH TEMPERATURES. COMPOUNDS WITH A HIGH ANTIBRONZING EFFECT ARE COMPOUNDS OF THE 2-MERCAPTO-5-UREIDO-1,3,4-THIADIAZOLE SERIES.

United States Patent 3,726,680 PROCESS FOR THE PRODUCTION OF PHOTO- GRAPHIC IMAGES IN THE PRESENCE OF COMPOUNDS OF THE THIADIAZOLE SERIES Anita von Konig, Leverkusen, and Carl Metzger, Wuppertal-Elberfeld, Germany, assignors to Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany No Drawing. Filed May 19, 1970, Ser. No. 38,916 Claims priority, application Germany, June 14, 1969, P 19 30 338.9 Int. Cl. G03c 7/00 US. Cl. 9652 Claims ABSTRACT OF THE DISCLOSURE Processed photographic silver images are stabilized by the addition of antibronzing agents against loss of density and changes in image tone upon high gloss drying at high temperatures. Compounds with a high antibronzing effect are compounds of the Z-mercapto-S-ureido-l,3,4-thiadiazole series.

PROCESS FOR THE PRODUCTION OF PHOTO- GRAPHIC IMAGES The invention relates to a process for the production of photographic images which includes drying mechanically at high temperatures on a high gloss press in effective contact with anti-bronzing agents of the mercapto triazole series.

The silver images obtained from light-sensitive silver halide emulsion layers often undergo changes during high gloss drying or during mechanical drying at high temperature. 'Ihus commonly a loss in density occurs or blueblack image tones change to brownish tones and brown tones change into greenish black tones. These changes are known as partial burning or bronzing of the silver image.

The incorporation of small quantities of certain chemical compounds, known as anti-bronzing agents, into the light-sensitive material which contains a silver halide emulsion copying layer is known. These compounds alternatively may be added to the treatment baths which are used for the material to prevent this loss of density.

The known anti-bronzing compounds are however, only of limited utility either because their anti-bronzing effect is not sufiicient or because they impair the photographic properties.

It is among the objects of the present invention to provide new anti-bronzing agents which have a sufiiciently large anti-bronzing effect and which do not deleteriously effect the photographic properties of the material.

We now have found that Z-mercapto-S-ureido-l,3,4- thiadiazole of the following formula are excellent antibronzing agents:

s R-NHC ONHT n-sn or the tautomeric Z-thione compounds wherein R stands for (1) a saturated or olefinically unsaturated aliphatic group containing 1-12 carbon atoms, preferably 1-6 carbon atoms which may be substituted with phenyl, alkoxy or halogen such as fluorine, chlorine or bromine (2) an aryl group especially a phenyl or naphthyl group, or (3) cycloalkyl such as cyclohexyl, these aryl and cycloalkyl radicals, being substituted if desired, eg with alkyl or alkoxy groups both of which advantageously contain up to 5 carbon atoms, sulfo or halogen atoms such as uoriner, chlorine or bromine.

'ice

Suitable compounds are shown 1n the following table:

Decomposition point,

No. R C.

1 CH3 264 2 C2H5 274 3 CHz-O-CHa 236 4 CH2CH2CH: 214 5- CH2CH=CH2 230 6- Cyclohexyl 204 7- Phenyl 280 8--. Naphthyl-(l) 242 9 014B 143 10 01511 3 145 CmH 7 149 Examples of preparation of these compounds are as follows: 74.4 g. (0.44 mol) of fl-naphthylisocyanate are added dropwise to 53.2 g. (0.4 mol) of 2-mercapto-5- amino-1,3,4-thiadiazole in 200 ml. of dimethylformamide. The reaction mixture is then stirred for one hour at 50 C. After evaporation of the solvent, the residue is dissolved in 10% aqueous sodium hydroxide solution, clarified with animal charcoal and then adjusted to pH 5 with dilute hydrochloric acid. l-naphthyl-3-(2-mercapto-1,3,4- thiadiazolyl-S urea separates. This can be further purified by recrystallization from alcohol. Melting point 242 C., yield 100 g. (83% of theoretical).

The anti-bronzing agents are advantageously added in dissolved form to the light-sensitive silver halide emulsion layer after chemical ripening or to the finished casting solution. Water, aqueous solutions of alkali metal hydroxides, lower aliphatic alcohols, for example those having up to 3 carbon atoms, dimethylformamide or mixtures thereof are used as solvents.

The anti-bronzing agents may also of course, be added to other photographic layers or to treatment baths, for example to the developer or fixing bath, or to an additional hardening bath or to a bath which contains surface active compounds and which is used as final bath before drying on the high gloss press or drying at elevated temperature.

The concentration of anti-bronzing agents in the layers or in the treatment baths may vary within wide limits. The concentration depends on the effect required, the nature of the reproduction process or the composition of the photographic material. When these agents are used in a photographic layer, particularly in the silver halide emulsion layer, quantities of 20 mg. to 1 g. per mol of silver halide have been found sufficient. Concentrations of between 200 and 700 mg. of anti-bronzing agent per mol of silver halide are preferred.

When the anti-bronzing agents are used in the treatment baths, they are advantageously added in the form of their alkali metal salts. Optimum concentrations can easily be found by a few simple laboratory tests. When such tests were carried out, concentrations of between 10 and 100 mg. per liter of treatment bath were found to be sufiicient. When the anti-bronzing agents are added to the developer bath, quantities of between 20 and 50 mg./l. are generally sufiicient. When the exposed photographic material is passed through a bath which contains the anti-bronzing agent, it absorbs a certain quantity of the compound in its water-permeable layers. The anti-bronzing agent diffuses into the layer which contains the silver image and is present during the heat drying. The anti-bronzing effect obtained in this way is just as good as that obtained when the compound is added directly to the silver halide emulsion layer.

The usual silver halide emulsions are suitable for the present invention. The silver halide may be silver chloride, silver bromide or mixtures thereof, if desired with a small amount of silver iodide of up to 10 mols percent.

The binder used for the photographic layers is preferably gelatin but this may be partly or entirely replaced by other natural or synthetic binders. Examples of natural binders are alginic acid and derivatives thereof such as salts, esters or amides, cellulose derivatives such as carboxymethylcellulose, aikyl cellulose such as hydroxy ethyl cellulose, starch or its derivatives such as ethers or esters or carragenates. Polyvinyl alcohol, partly saponified poly- 323 may also be used as chemical sensitizers.

The emulsions may also be chemically sensitized, for example by after-ripening in the presence of compounds which contain sulfur, for example allyl isothiocyanate, allyl thiourea, sodium thiosulfate and the like. Reducing agents, for example, the tin compounds mentioned in Belgian Pats. Nos. 493,464 or 568,687 or polyamines such as diethylene triamine or aminomethanesulfinic acid derivatives, for example, according to Belgian Pat. No. 547,- 323 may also be used as chemical sensitizers.

Noble metals and noble metal compounds such as gold, platinum, palladium, iridium, ruthenium or rhodium are also suitable as chemical sensitizers. This method of chemical sensitization is described in the article by R. Koslowsky, Z. Wiss. Phot. 46, 6572 (1951).

The emulsions may also be sensitized with polyalkylene oxide derivatives, e.g. with polyethylene oxide of molecular Weight between 1,000 and 20,000 or with condensation products of alkylene oxides with aliphatic alcohols, glycols, cyclic dehydration products of hexitols, alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides. The condensation products have a molecular weight of at least 700 and preferably more than 1000. These sensitizers may, of course, be applied in admixture with each other in order to achieve special effects, as described in Belgian Pat. No. 537,278 and in British Pat. No. 727,982..

The emulsions may also be optically sensitized, for example with the usual polymethine dyes such as neutrocyanines, basic or acid carbocyanines, rhodacyanines, hernicyanines, styryl dyes, oxonoles and the like. Sensitizers of this type are described in The Cyanine Dyes and Related Com-poun by F. M. Hamer (1964).

The emulsions may contain the usual stabilizers such as homopolar or salt-type compounds of mercury with aromatic or heterocyclic rings such as mercaptotriazoles, simple mercury salts, sulfonium mercury double salts and other mercury compounds. Azaindenes, especially tetraor penta-azaindenes and in particular those which are substituted with hydroxyl or amino groups are also suitable for use as stabilizers. Compounds of this type are described in the article by Birr, Z. Wiss. Photo. 47, 2-58 (1952). Other suitable stabilizers include heterocyclic mercapto compounds, e.g. phenyl mercapto tetrazole, quaternary benzothiazole derivatives, benzotriazole and the like.

The emulsions may be hardened in the usual manner, for example with formaldehyde or halogen-substituted aldehydes which contain a carboxyl group, such as mucobromid acid, diketones, methanesulphom'c acid esters, dialdheydes and the like.

EXAMPLE 1 An unrinsed chlorobromide gelatin emulsion (20 mol percent of AgBr) which contains per liter 0.18 mol of silver halide, 2 ml. of 1% alcoholic solution of l-phenyl- 'S-mercapto-tetrazole, 20 m1. of a aqueous saponin solution and 2 ml. of a 30% aqueous Formalin solution is divided into 6 portions. To each portion is added an anti-bronzing agent of the present invention dissolved in dimethyl formamide. Details are given in the following table.

The emulsions are applied onto a baryta-coated paper support and dried. The layer contains 1.5 to 1.6 g. silver per m? in the form of silver halide.

Comparison strips of the photographic material thus obtained is exposed in a sensitometer customarily employed in the art. The exposed samples are developed in a developer of the following composition (temperature 18 C., developing time seconds):

1 g. of p-methylaminophenol 3 g. of hydroquinone 13 g. of anhydrous sodium sulfite 26 g. of sodium anhydrous carbonate 1 g. of potassium bromide dissolved in water and made up to 1000 ml.

The developed material is fixed for 10 minutes in an aqueous solution of sodium thiosulfate and rinsed.

The moist material is dried on a high gloss press heated to 130 C. Whereas the high gloss drying causes a color change from brown to greenish brown to blue in the control sample (without addition), the brown image tones do not change if a compound according to the invention is present. The maximum density of the different materials is determined with a densitometer of an air-dried sample as compared with a material dried on a glazing press. The following results are obtained:

Maximum density Concentration, Heat glazed Compound N o. rug/kg. Air dried and dried Control sample--- 0 2. 31 1. 69 66 2.32 1.85 61 2. 28 1. 93 68 2. 28 1. 86 114 2. 31 2. 18 136 2. 30 2. 20

EXAMPLE 2 Maximum density Concentration, Heat glazed Compound No. rug/kg. Air dried and dried Control sample--- 0 2. 05 1. 68 82 l. 98 1. 95 78 1. 98 l. 97 97 2. 03 2.05 95 2. 05 2. 12 113 2.05 2. 15

EXAMPLE 3 Comparison strips of the photographic material of the control sample of Example 1 which do not contain any anti-Bronzing agents are developed in different developer compositions.

The developer had the basic composition as described in Example 1.. The different samples, however, contain an anti-bronzing agent of the present invention in the amount indicated in the following table. The processing is accomplished as described in Example 1. The following results are obtained:

Maximum density Concentration, Heat glazed Compound No. mgJkg. Air dried and dried Whereas the high gloss drying produces a color change to a color varying from greenish brown to blue in the control sample, the warm brown image tone remains unchanged when developed in a developer containing an antibronzing agent.

EXAMPLE 4 The experiments are performed as described in Example 3 with the exception however, that the anti-bronzing agents are added to a fixing bath of the following composition:

Fixing bath 200 g. of sodium thiosulfate cryst.

20 g. of potassium metabisulfite dissolved in water and made up to 1000 ml.

The fixing bath is divided into 3 equal parts before mixing. The compounds shown in the table below are added to the parts. The following results are obtained:

Maximum density Concentration, Heat glazed Compound No. mgJl. Air dried and dried Control sample.-- 2. 31 l. 69 1 20 2. 31 2. 40 2 20 2. 31 2. 42

sisting of hot drying the processed layer containing thesilver image in effective contact with a 2-mercapto-5- ureido-1,3,-4-thiadiazole of the following formula:

or the tautomeric 2-thi0ne compounds wherein R stands for a saturated or olefinically unsaturated aliphatic group containing 1-12 carbon atoms, a radical of the phenyl or naphthyl series or cycloalkyl.

2. The process of claim 1, wherein the silver halide emulsion layer contains the Z-mercapto-S-ureido-l,3,4- thiadiazole.

3. The process of claim 1, wherein a processing bath contains the 2-mercapto-5-ureido-1,3,4-thiadiazo1e.

4. A light-sensitive photographic material having at least one supported silver halide emulsion layer, which contains a Z-mercapto-S-ureido-1,3,4-thiadiazole of the following formula:

s R-NHCONHT T311 or the tautomeric 2-thione compounds wherein R stands for a saturated or olefinically unsaturated aliphatic group containing 1-12 carbon atoms, a radical of the phenyl or naphthyl series or cycloalkyl.

5. An aqueous photographic developing or fixing bath containing a Z-mercapto-S-ureido-1,3,4-thiadiazole of the following formula:

or the tautomeric 2-thione compounds wherein R stands for a saturated or olefinically unsaturated aliphatic group containing 1-12 carbon atoms, a radical of the phenyl or naphthyl series or cycloalkyl.

References Cited UNITED STATES PATENTS 2,573,027 10/ 1951 Kendall 9652 2,743,184 4/1956 Kendall .96-52 3,020,155 2/1962 Yackel 9658 3,212,892 -10/ 1965 Von Konig 96-61 3,314,789 4/ 1967 White 96-52 FOREIGN PATENTS 836,285 6/1960 Great Britain 96-109 940,169 10/1963 Great Britain 9666.5 1,186,441 4/1970 Great Britain 96-109 NORMAN G. TORCH-IN, Primary Examiner J, R. HIGHTOWER, Assistant Examiner US. Cl. X.R.

UNITED STATES PATENT oTTTcE TIERTEHQATE Di TCORRECHDN Patent No. 3326 680 Dated April 10, 1973 Inventor) Anita von Konig et 3,1

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, lines 28 and 29, triazole" should read thiadiazole Column 3, line 9, the entire line is incorrect and should read as follows: vinyl acetate, polyvinyl pyrrolidone and the like may be mentioned as synthetic binders,

Signed and sealed this 18th day of December 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissioner of Patents F ORM PO-105O (10-69) USCOMM-DC 60376-P69 u 5 GOVERNMENT PRINTING OFFICE I969 0366334. 

